gluSphere draws a sphere of the given radius
centered around the origin. The sphere is subdivided around the z axis into
slices and along the z axis into stacks (similar to lines of longitude
and latitude).

If the orientation is set to GLU_OUTSIDE (with gluQuadricOrientation),
then any normals generated point away from the center of the sphere. Otherwise,
they point toward the center of the sphere.

If texturing is turned on (with
gluQuadricTexture), then texture coordinates are generated so that t
ranges from 0.0 at $ z ~=~ -^"radius" $ to 1.0 at $ z ~=~ "radius" $ (t increases
linearly along longitudinal lines), and s ranges from 0.0 at the +y axis,
to 0.25 at the +x axis, to 0.5 at the -y axis, to 0.75 at the -x axis, and
back to 1.0 at the +y axis.